Photographic flash equipment of the battery-condenser type



Dec. 3l, 1957 2,817,963

FRIEDRICH-WILHELM SCHOLKEMElER PHOTOGRAPHIC FLASH EQUIPMENT-0F THEBATTERY-CONDENSER TYPE Filed DSC. 16, 1953 United States PatentPHOTOGRAPHIC FLASH EQUIPMENT OF THE BATTERY-CONDENSER TYPEFriedrich-Wilhelm Scholkemeier, Braunschweig, Germany, assignor toFranke & Heidecke, Fabrik Photographischer Przisions-Apparate,Braunscliweig, Germany, a firm Application December 16, 1953, Serial No.398,561

Claims priority, application Germany December 17, 1952 11 Claims. (Cl.67-31) This invention relates to photographic ash equipment of the kindoften referred to as the battery-condenser type, in which a smallbattery is used to charge an electric condenser or capacitor, and inwhich the electrical energy stored in the condenser or capacitor is usedto ignite or re the flash bulb. Apparatus of this general type is known,but such apparatus in the previously known forms is not entirelysatisfactory, particularly when it is desired to connect one or moreadditional or supplementary flash bulb sockets to the socket of the mainor primary flash bulb.

Among the diiculties likely to arise upon the use of additional orsupplementary bulbs in apparatus as heretofore used, may be mentionedthe following: If the supplementary bulb is connected in parallel withthe main bulb, there is no longer any complete assurance of firing,inasmuch as the discharge current of the condenser is split up among twoor more parallel paths. Thus firing failures are likely to result,particularly if different types of flash bulbs are used in differentsockets. If one or more additional flash bulbs are connected in parallelto the series connection of the main bulb and its condenser, theadditional bulbs form a closed circuit with the condenser and the mainash bulb, so that if the additional bulbs are inserted in their socketsafter the main bulb has already been inserted in its socket, all of thebulbs are likely to be fired at the moment of the last connection. `Onthe other hand, if the additional bulbs, with this arrangement, areinserted in their sockets lirst, and the main bulb is inserted last,then no charging of the condenser will take place, as the chargingcurrent will be shunted through the additional bulbs, so that a failureof firing of all the bulbs will result. Or again, if each additionalbulb is provided with its own condenser in series with the bulb, and ifall of the additional bulbs and their series condensers are connected inparallel to the battery, a failure to lire is also possible. Upon theinsertion, at the latest, of the third bulb in its socket, a firing ofat least this third bulb is likely to occur since the condensers of therst two bulbs have meanwhile become charged, and will discharge n apulse-like manner into the newly connected condenser upon insertion ofthe third bulb.

An object of the present invention, therefore is the provision ofgenerally improved and more satisfactory photographic flashlightapparatus of the batterycondenser type, so designed and constructed asto permit the convenient and reliable use of any desired number (withinreason) of additional or supplementary ash bulbs, in combination withthe main or primary flash bulb.

Another object is the provision of such apparatus or equipment sodesigned and constructed that premature firing or failure to re will notoccur, regardless of the order in which the various bulbs are insertedin their sockets or holders.

A further object is the provision of simple photoflash equipmentsuitable for use with electrolytic condensers, including a switch tointerrupt the residual current which ,tends to ow through condensers ofthe electrolytic type.

A still further object is the provision of a construction in which theswitch for interrupting the residual current is built into one of thebulb sockets so as to be automatically operated by insertion or removalof the flash bulb.

These and other desirable objects may be attained in the mannerdisclosed as an illustrative embodiment of the invention in thefollowing description and in the accompanying drawings forming a parthereof, in which:

Fig. l :s a diagrammatic or schematic view of a construction inaccordance with a preferred embodiment of the invention; and

Fig. 2 is a schematic drawing of part of the construction shown in Fig.l, illustrating additional details.

The same reference numerals throughout the several views indicate thesame parts.

Referring first to Fig. 1 of the drawings, there is here showndiagrammatically llash equipment in the form of a main flash unit orflash gun comprising the parts within the dotted rectangle 41, withprovision for adding supplementary or additional flash units or flashguns of any desired number, as shown by the parts outside of therectangle 41. The main unit or primary unit includes, within a suitablecasing or frame, a battery 1 (for instance, a battery providing 22.5volts) connected in circuit with a protective resistance 2 (forinstance, a resistance of 2500 ohms), the circuit further extendingthrough a switch 12 to a condenser or capacitor 3 (having a capacitance,for instance, of microfarads), the circuit from the condenser 3 back tothe battery 1 having in series a resistance 15 of a value, for example,of 2500 ohms. Arranged in parallel with the resistance 15 is the socketfor the main or primary flash bulb 4.

A switch 5 is connected across the main circuit above mentioned, bymeans of switch wires 30 and 3,1, the former leading from the switch tothe main circuit at a point between the resistance 2 and the switch 12,and the other wire 31 leading from the other side of the switch 5 t0 themain circuit at a point between the battery 1 and the socket of the mainash lamp 4. This switch 5 is the main control switch or operating switchfor tiring the flash bulb or bulbs. It is here shown diagrammatically asa simple single pole switch mounted on the main unit 41, although inactual practice this main ring switch 5 is usually the synchronizerswitch built into the photographic shutter on the camera with which theflash equipment is used, or is a switch forming part of a separatesynchronizer attached to and operating with the shutter of such camera,as well understood in the art.

With this arrangement, if the switch 12 is closed, the `condenser orcapacitor 3 becomes charged from the battery 1, through the resistances2 and 15, if no bulb is present in the socket of the bulb 4. However, ifa bulb is present, the condenser becomes charged through the bulb, whichis in parallel with the resistance 15 and which, when present, serves toshort circuit the resistance 15, since the resistance 15 has a valueconsiderably higher than the internal resistance of the bulb 4.Preferably the switch 12 is closed automatically by insertion of thebulb 4 into its socket, and is opened automatically by removal orejection of the bulb from its socket, in the manner `disclosed below.

With the condenser 3 fully charged, the closing of the switch 5 willallow the charge in the condenser 3 to ow through the bulb 4, thustiring the bulb in the desired manner. As soon as the bulb is tired andthe switch 5 is again opened, the condenser 3 is immediately rechargedif the switch 12 remains closed. But upon opening the switch 12, byejection or removal of the bulb from its socket, the circuit from thebattery to the condenser is broken and thus there is no wastage ofcurrent from the battery while there is no lamp in the socket, whichwastage would otherwise occur if the switch 12 3 were not present, onaccount of the residual current characteristics of the condenser 3 ifthis condenser is of the electrolytic type. v

For enabling connectionl of anydesirednurnber of vadditional orsupplementary f flash units,y the Vterminals k8 and- 9 are provided, ot`any suitable form s uch as male yand female plug terminalsordbavyonetjoint terminals. .The terminal Svis connected to the switch-sideof the condenser 3 while the'lterminal is connected to thebatteryside ofthe bulb- 4 and iresistance 15. Each supplementary unitcomprises a dash bulb socket and acon- .denser s in iseries with each,,o ther, yto ,bel connected across theterrninals 8 a ndr 9,` yand aresistancein parallel around the bulb socket, the resistance being ofgreaterresistance .than .that of the-.flash bulb,vv justjas in the caseof the resistance w hi ch isffobgreater resistance-. than the bulb 4..Thus, forexample,-.the lampf6 and, condenser 10 of one supplementaryunitware. connected across the terminals .8f and 9, Vin serieswith leachother, ,andj with a resistance 16 in ,parallel around the 4 socket .fofz`thev AIlamp f 6. If a; secondsupplementaryunit is to be `used,.:the`socket of its lamp-7 is connected yin series with the con- ,de'riser11, likewise across the terminals and 9 and in` parallellwith-.the .lamp6 and condenser10, anda supplernfentary ,resistance-.17 is .connectedinfparallel aroundthe larnp- 7, a'sshownin Fig. l. .Any desired num-.ber" (within, reason) of 4additional supplementarylunits may be addedin the same way.

rIf the supplementary unit or ur 1i ts are cor 1nected acrossthefterminals 'and'9 of-,the mainunitoinash gun 41, vin ,thernannershowm it isseen that all of thecondensers 3, 10,.`and lliwillbechargedbyk the battery 1, as soon as tl1e .s.wit`ch`1 2 isf-closedv(or` as .soon as the, supplementary Aunits are connected Ito, the mainunit,-;if the switch 412 is already' closed) regardless of whether`there are-bulbs in the` various. sockets and. regardless of `thefc'rderffin which,lmlbsfbr,freshA bulbs are inserted .in thevarioiisjsockts,'fo ineach` case thecondensers 3,10, and `11 are"charged through'fftheir Yrespective rsistances 15, 1'6, and l17,.itlrnol bulbs `orf'if burned out bulbs are present. Thus'the order orsequencein which bulbs areinserted isimmaterial,` due to theprovision ofthe rsistances, andthe electric equilibrium is'not disturbed by theinsertion of new bulbs.

As already mentioned, `the switch 12 is preferably operatedautomatically fbyinsertion of thebulb 4 in its "socket, or removal` o`fthe bulb'frbm"the socket. Thisfis shown dia'grammatically vin Fig. r1,'and 'in somewhat 'g'rea'terstructural detail in Fig. 2'.VThe-baise",'contact "'14 of the lbulb Vsocketfisfformed on '-a Aleafsprin'glwhich also carries the insulating.; plate 24 on which one'side12 of the switch is'c'arriedf The axial insertion'of the fshankr of thebulb 4 into its',soc`kt"21`causes -the cenftral vcontact." 23,0f` theQbulb 'to press 4on Vthe centralfcontact member 22 Aof the4 socket (themember 22 being 'fo'rrned `on the'spring 14 and thereby/lle'xes` the.spring "14, carrying the insulating plate`24"`andthe switchpart 12 in adownwardV yc`li'rectic`1n` when viewed asin Fig. 2, until, the switchApart 12 comes Ainto contact witlia spring 'arm 25 constituting theotherv'side of this switch. `Thus ythe switch is closed uponinsertion of thebulb 4, and tsprings fopen again when the bulb 4 is removed or ejected..The bulb, as customary, is held in the socket by 'means of a bayonetslot in the side walls of 4the socket engaging radial pinsor projectionson the shank ',ofthe bulb, althougha screw type of bulb shank andsocketcould be used if desired. The contact -mernber 25 constituting theother side of the switch 12 is inthe form of a wiperv arm constantly`pressing vagainst'and 'in conductive relation to the,co 'nffductingldisk'vZ torinedcn. onel sideQofthe cable drum "or lcordd'rurri` 2 7 which is rotatively vsupported on the "housing 28y oftheiiash gun or 'ashunit Cin (the drum 27 "isA reeled 'the two wireelectric cable .orjcord 29 containi'ng the wires,30, andf31whichleadasiabove inengermana tioned, to the main ring switch 5 which islocated on the associated photographic camera or its shutter. The wire30 is electrically connected to the disk 26 so that it is conductivelyconnected to the spring 25, while the other wire 31 of the cable 29siselectrically connected to the metal disk 32 which makes connection withthe lamp housing 28, thus being grounded on the housing of the flashunit, which constitutes one side of the electric circuit. A hand wheelor knob 43, mounted on the shaft o-f the reel 27 and laccessibleexternally of the Ycasing 28, serves for manually turningthe reel27` towind up the core 29 when the ash gun or unit is disconnected from thecamera.

In the preferred arrangement, as above set forth, there isa protectiveresistance 15, 16, 17 connected in parallel around each of the ashbulbs. 4, 6, and 7, respectively. This is preferred because with thisarrangement it is immaterial in which order or sequencethe various bulbsvare renewed, after tiring. But if the operator takes 'care to insertthe *fresh bulbs in the `supplementary flash [guns first, and then toinsert a fresh bulb 4 in the main ilash gun after the supplementary gunbulbs have been replenished, the supplementary units can be used safelyin connection with an old fstyle `flash unit which does 4not have Atheprotectivefresistance 15. With such an arrangement, the condensers 10and 11 of the supplementary units will be charged before ythe bulb 4 ofthe main unit is renewed, and then when the main bulb is renewed it willnot be prematurelyred. Hence the supplementary units of the presentinvention have the double advantage that they, can lbe succe ssfullyemployed also with a main unit or a'sh vgun ofthe standard type` inaccordance 'with they prior art, but 'the vgreatest advantages ofl thepreseutfinventionare achieved, of course, when the supplementaryunits inaccordance 'with the present invention are employed Iwith a` main unitwhich v is 'alsoof the "new Vkind/in accordance with the presentinvention.

Since it has been j-mentionedjabo've, that a red ash bulb is replaced bya fresh bulb, it will be apparent to those skilled in the art that theHash bulbs in question are of the ordinary` photoilash type, having aglass envelope filled withshredded foil or wire made of magnesium orother combustible material. Thus these photoilash bulbs may bereferredtoas bulbs of the combustible and'consumable type, `usable only once, asdistinguished from the gas filled multiple Hash type of bulb which may.b e vflashed repeatedly vand is not limited to a single Hash operation.'The problems to be solved Vin dealing with bulbs of the consumable typeare different from` thoseencountered in gasflled bulbs of the repetitivetype, yfor the latter 'will conduct no'current until a certain criticalvoltage is reached, whereas the ordinary photoflash bulbs oftheconsumable type have a relatively low internal resistance and willconduct some current at any voltage. It isthis fact which accounts forcertain types of misring 'or malfunctioning of photoflash apparatus whenusing consumable bulbs, and which accounts for the fact that variouselectricircuit'arrangements which are suitable for use with gaslledrepetitive flash bulbs are not suitable for use with photoflashl bulbsof the ordinary combustible or Yconsumable type.

It is seen from the foregoing disclosure that the above mentionedobjects of the inventionare well fulfilled. It

`its feed ycontacts-21, 22 beforethe members 1 4, 24 are displacedfarrenough toY close the Thevalues of the condensers `or ca; acitorsinrthesupresistors therein, are preferably substantially the same asthose in the main unit. Thus thecapacitors 3, 10, and 11 preferably allhave a capacity of about 100 microfarads, or in the order of magnitudeof about 100 to 200 mf. The resistors 15, 16, and 17 preferably all haveresistances of about 2500 ohms, these resistances being substantiallyhigher than the internal resistances of the photoash bulbs 4, 6, and 7.

What is claimed is:

l. A supplementary photographic ash unit for electrical connection inparallel with a photoash bulb and condenser of a main Hash unit of thebattery-condenser type, said supplementary unit comprising asupplementary socket for holding a supplementary photoash bulb, asupplementary condenser electrically connected in series with saidsocket, a protective resistor electrically connected in parallel withsaid socket and in series with said supplementary condenser, saidresistor having a resistance substantially larger than that of aphotoash bulb intended to be used in said supplementary socket, andelectrical leads for connecting one side of said supplementary condenserand the remote sides of said supplementary socket and resistor to a mainash unit.

2. A photographic flash unit comprising an electric circuit including abattery, a condenser, and a photoflash bulb socket all in series witheach other, a protective resistor arranged in said circuit in parallelwith said bulb socket and in series with said battery and condenser, theresistance of said resistor being greater than the resistance of thephotoflash bulb used in said socket, and an electric switch operativelyinterposed in said `circuit between said battery and said condenser.

3. A photographic flash unit comprising an electric circuit including abattery, a condenser, and a photoash bulb socket all in series with eachother, a photoash bulb of the consumable non-repetitive type operativelyconnected in said socket, a protective resistor arranged in said circuitin parallel with said bulb socket and in series with said battery andcondenser, the resistance of said resistor being greater than theresistance of the photoash bulb used in said socket, a bulb firingcircuit operatively connecting the respectively remote sides of saidcondenser and said socket to each other independently of said battery,and a tiring switch in said tiring circuit to open and close the same.

4. A construction as defined in claim 3, in which said firing switch ismounted on a photographic camera and in which said phototlash bulb is soplaced as to illuminate the scene to be photographed by the camera, andin which said firing circuit includes a flexible cord extending fromsaid flash unit to the camera on which said switch is mounted, said unitfurther including a built-in reel on which said cord may be wound whennot in use, and an externally accessible handle for turning said reel towind said cord thereon.

5. A photographic ash unit comprising an electric circuit including abattery, a condenser, and a photoflash bulb socket all in series witheach other, a protective resistor arranged in said circuit in parallelwith said bulb socket and in series with said battery and condenser, theresistance of said resistor being greater than the resistance of thephotoash bulb used in said socket, and a supplementary flash unit forelectrical connection to said first mentioned unit for tiringsimultaneously therewith, said supplementary unit including asupplementary socket for holding a supplementary photoash bulb, asupplementary condenser electrically connected in series with saidsupplementary socket, a supplementary resistor electrically connected inparallel with said supplementary socket and in series with saidsupplementary condenser, said supplementary resistor having a resistancegreater than the resistance of the photoash bulb used in saidsupplementary socket, and circuit connections for electricallyconnecting the respectively remote sides of said supplementary condenserand supplementary socket re- 6 spectively to the corresponding sides fsaid condenser and socket of said first mentioned unit.

6. A construction as defined in claim 2, further including means forautomatically closing said switch upon insertion of a photoflash bulbinto said socket and opening said switch upon removal of a bulb fromsaid socket.

7. A construction as defined in claim 6, in which said bulb socketincludes two feed contact members for making electrical contact with aphotoflash bulb inserted into said socket, and in which said meanscloses said switch only after a bulb, during insertion in said socket,has made contact with both of said feed contact members.

8. A supplementary photographic ilash unit for electrical connection inparallel with a main photoash bulby of the combustible and consumabletype and with a con-- denser of a main flash unit of thebattery-condenser type, said supplementary unit comprising asupplementary bulbA socket, a supplementary photoash bulb of thecombustible and consumable type electrically connected in said socket, asupplementary condenser electrically connected in series with saidsocket and with said supplementary' in series with said supplementarycondenser, said resistor having a resistance substantially larger thanthat of said supplementary bulb, and electrical leads for connecting theside of said supplementary condenser which is remote from saidsupplementary bulb and the sides of said supplementary socket andresistor which are remote from said supplementary condenser to a mainflash unit.

9. The combination with a main photoas'h unit comprising a source ofcurrent, a rst resistor and a main photoliash bulb electricallyconnected in series with each other and with said source, a secondresistor electrically connected in parallel with said photoash bulb andin series with said rst resistor and said source, and a main condenserelectrically connected in series with said source, rst resistor, andsecond resistor, of a supplementary photoash unit comprising asupplementary condenser and a supplementary photoflash bulb electricallyconnected in series with each other and in parallel with said maincondenser and main photoash bulb, and a supplementary resistorelectrically connected in parallel with said supplementary bulb inbypass relation thereto, said supplementary photoflash unit having noyseparate source of current of its own.

l0. The combination with a main photoash unit comprising a source ofcurrent, a rst resistor and a main photoash bulb electrically connectedin series with each other and with said source, a second resistorelectrically `connected in parallel with said p'hotoash bulb and inseries with said iirst resistor and said source, and a main condenserelectrically connected in series with said source iirst resistor, andsecond resistor, of a supplementary phototlash unit comprising asupplementary condenser and a rsupplementary photoash bulb electricallycon-- nected in series with each other and in parallel with said. maincondenser and main photoflash bulb, and a sup-A plementary resistorelectrically `connected in parallel withA said supplementary bulb inbypass relation thereto, said.

supplementary photoash unit having no separate source of current of itsown, said photoflash bulbs being of the combustible and consumable type,and all of said con-- densers being of the electrolytic type.

1l. A construction as defined in claim 10, further including an electricswitch in the series connection between. said source of current and saidmain condenser, a bulb socket for said main phototlash bulb, and meansoperated by insertion of said main bulb in said socket for closing saidswitch and operated by removal of said main bulb` from said socket foropening said switch.

(References on following page) v,Schwartz, .May 19,1953

